A protein phosphoenzyme (kinase) is essential for intracellular signal transduction, and abnormal expression or abnormal activation of the protein phosphoenzyme has been known to give rise to various diseases. Therefore, a wide variety of phosphoenzymes attracts attention as target agents for innovative drug development, and inhibitors specific to target phosphoenzymes are being searched for all over the world.
For example, Patent Document 1 discloses benzothiazole derivatives that can inhibit the phosphorylation activity of phosphoenzymes Clk1 and Clk4. Patent Document 2 discloses benzothiazole derivatives that can inhibit the phosphorylation activity of a phosphoenzyme DYRK.